Teams such as the Decatur Staleys, Hammond Pros, Chicago Tigers and the Cardinals had formed an informal loop similar to, and generally on par with, the Ohio and New York circuits that had also emerged as top football centers prior to the league's founding.

The person keeping the minutes of the first league meeting, unfamiliar with the nuances of Chicago football, recorded the Cardinals as from Racine, Wisconsin.

[2] Thus, in the first six years of the NFL's existence, the Bears-Cardinals games had a direct impact on the league championship 4 times.

At season's end, after losing in a Chicago snow storm to the Pottsville Maroons 21–7, the Cardinals found themselves in second place.

Hoping to improve their record, they scheduled and won two hastily arranged games against weaker teams, the Milwaukee Badgers and the Hammond Pros.

Meanwhile, because Pottsville had played an unauthorized exhibition game in Philadelphia against the University of Notre Dame All-Stars, the Maroons were stripped of the title.

Later, it was offered to the Cardinals, whose owner, Chris O'Brien, refused to accept the championship title for his team.

The Chicago Cardinals were one of the few NFL teams to host African-American players in the 1920s—most notably Duke Slater.

Between 1926 and 1927 a movement began among the owners of the NFL to follow the racist example of professional baseball and in 1927 every African-American player was out of the league, with the sole exception of Duke Slater.

[8] On November 28, 1929, Slater participated in an NFL record as a lineman in front of Ernie Nevers in a game in which he scored six rushing touchdowns in a 40–6 victory over the Chicago Bears.

[7] Slater played all 60 minutes of the contest, alternating between the offensive and defensive lines as well as participating on special teams.

[9] The Cardinals posted a winning record only twice in the 20 years after their 1925 championship (1931 and 1935); including 10 straight losing seasons from 1936 to 1945.

In 1944, owing to player shortages caused by World War II, the Cardinals and Pittsburgh Steelers merged for one year and were known as the "Card-Pitt", or derisively as the "Carpets" as they were winless that season.

This would be the most celebrated year in Cardinals history as the team went 9–3, beating Philadelphia in the championship game 28–21 with their "Million Dollar Backfield", which included quarterback Paul Christman, halfback Charley Trippi, halfback Elmer Angsman, and fullback Pat Harder, piling up 282 rushing yards.

Prior to the season he had beaten the Chicago Rockets of the upstart All-America Football Conference for the rights to Trippi.

The next year, Violet Bidwill married St. Louis businessman Walter Wolfner, and the Cardinals fell to 6–5–1.

With the team almost bankrupt, the Bidwills decided to cede Chicago to the Bears and move the Cardinals to another city.

Needing cash, the Bidwills entertained offers from various out-of-town investors, including Lamar Hunt, Bud Adams, Bob Howsam and Max Winter.

Having failed in their separate efforts to buy the Cardinals, Hunt, Adams, Howsam and Winter joined forces to form the American Football League.